Thermosetting electrostatographic developer of a carrier and preploymer of diallyl phthalate, isophthalate and mixtures

ABSTRACT

ELECTROSTATOGRAPHIC DEVELOPING POWDER (TONER) COMPRISED OF A FINELY-DIVIDED COLORED RESIN A SUBSTANTIAL PORTION OF THE RESIN BEING A SOLID, FREEFLOWING AND UNCROSSLINKED THERMOSETTING RESIN WHICH IS A POLYMER OF DIALLYL PHTHALATE, OR A POLYMER OF DIALLYL ISOPHTHALATE, PREFERABLY A HOMOPOLYMER OF DIALLYL PHTHALATE HAVING A SOFTENING RANGE OF 80* TO 105* C. OR A HOMOPOLYMER OF DIALLYL ISOPHTHALATE HAVING A SOFTENING RANGE OF 55*-95* C. THE USE OF THIS TONER IN CONJUNCTION WITH A CARRIER FOR THE DEVELOPEMENT OF A LATENT ELECTROSTATIC IMAGE PRODUCES A FINAL COPY HAVING IMPROVED STORAGE PROPERTIES.

United States Patent O THERMOSE'ITING ELECTROSTATOGRAPHIC DE- VELOPER OF A CARRIER AND PREPLOYMER F DIALLYL PHTHALATE, ISOPHTHALATE AND MIXTURES Robert J. Hagenbach, Rochester, and Robert W. Madrid, Macedon, N.Y., assignors to Xerox Corporation, Rochester, N.Y. No Drawing. Filed Feb. 4, 1970, Ser. No. 8,710

Int. Cl. G03g 9/02 U.S. Cl. 96-1.4 23 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates to electrostatography and more particularly to a new and improved composition and process for developing a latent electrostatic image.

Electrostatography is exemplified by the basic electrophotographic process taught by C. F. Carlson in U.S. Pat. 2,297,691, which involves placing a uniform electrostatic charge on a photo-conductive insulating layer, exposing the layer to a light and shadow image to dissipate the charge on the areas of the layer exposed to the light and developing the resulting latent electrostatic image by depositing on the image a finely-divided electroscopic material referred to in the art as toner. The toner is normally attracted to those areas of the layer which retain a charge, thereby forming a toner image corresponding to the latent electrostatic image, which may then be transferred to a support surface, such as paper. The transferred image is generally permanently affixed to the support surface, by heating although other suitable fixing means, such as solvent or overcoating treatment, may be substituted for the foregoing heat fixing step.

In automatic equipment, it is conventional to employ a photo-conductive plate in the form of a cylindrical drum which is continuously rotated through a cycle of sequential operations including charging, exposure, developing, transfer and cleaning. The plate is usually charged with corona with positive polarity by means of a corona generating device of the type disclosed by L. E. Walkup in U.S. Pat. 2,777,957 which is connected to a suitable source of high potential. After forming a powder image on the electrostatic image during the development step, the powder image is electrostatically transferred to a support surface by means of a corona generating device such as the corona device mentioned above. In automatic equipment employing a rotating drum, a support surface to which a powdered image is to be transferred is moved through the equipment at the same rate as the periphery of the drum and contacts the drum in the'transfer position interposed between the drum surface and the corona generating device. Transfer is effected by the corona generating device which imparts an electrostatic charge to attract the powder image from the drum to the support surface.

The polarity of charge required to elfect image transfer is dependent upon the visual form of the original copy ICC relative to the reproduction and the electroscopic characteristics of a developing material employed to effect development. For example, where a positive reproduction is to be made of a positive original it is conventional to employ a positive polarity corona to effect transfer of a negatively charged toner image to the support surface. When a positive reproduction from a negative original is desired, it is conventional to employ a positively charged developing material which is repelled by the charged areas on the plate to the discharge areas thereon to form a positive image which may be transferred by negative polarity corona.

The developers employed for developing the latent electrostatic image are basically a two component system consisting of a finely-divided electroscopic material (toner) which may be a finely-divided colored thermoplastic resin, and a carrier. The carrier is generally comprised of a core material, such as glass, and a triboelectric resinous coating with the toner particles being loosely held by the casing of the carrier by triboelectric action. The carrier and the toner are generally chosen so that the toner assumes a change of an opposite polarity to the electrostatic image, whereby upon passing the developer over the latent electrostatic image, the toner particles are attracted to the image being developed. Conversely, if the toner particles have a charge of identical polarity to the electrostatic image, the toner particles accumulate on the background portions.

The toner material must have in addition to the hereinabove noted electrostatic properties. certain chemical and physical properties. Thus, the preferred procedure for producing the final print involves heat fusion to melt the toner particles onto and into a transfer sheet and, therefore, the toner material must fuse within temperature limits tolerated by transfer members generally employed in the art, such as paper or the like, and after such heating, form a permanent image on the transfer member. In addition, the toner material should be friable to facilitate preparation of finely-divided particles thereof and compatible with other materials to permit easy modification of the physical characteristics thereof. Many toner materials having such properties, however, do not produce final images with the desired storage properties in that the toner images become tacky when stored in warm places or placed in contact with plasticized plastic surfaces.

SUMMARY OF THE INVENTION Accordingly an object of this invention is to provide an improved electrostatographic developing powder.

Another object of this invention is to provide an improved electrostatographic developing composition.

A further object of this invention is to provide for improved development of latent electrostatic images.

Still another object is to provide an electrostatographic developing powder which produces final images having improved storage properties.

These and other objects of the invention should be more readily apparent from the following detailed description thereof.

The object of this invention are broadly accomplished by providing a toner in which a substantial portion of the resinous'material thereof is solid, free-flowing uncrosslinked thermosetting resin which is either a polymer of diallyl phthalate, a polymer of diallyl isophthalate or a mixture of such polymers. The use of such a toner for .the development of a latent electrostatic image provides final copies having improved storage properties.

DETAILED DESCRIPTION OF THE INVENTION position containing a substantial portion of a freefiowing solid uncrosslinked thermosetting resin with the thermosetting resin being either a polymer of diallyl phthalate, a polymer of diallyl isophthalate or a mixture of these polymers. The polymer of diallyl phthalate or diallyl isophthalate may be either a homopolymer or copolymer, preferably a homopolymer, and if a copolymer, the diallyl phthalate and isophthalate may be copolymerized with each other or with co-monomers, such as, styrene, allyl laurate, vinylidene chloride, methyl methacrylate, acrylonitrite, and the like. The homopolymers and copolymers of diallyl phthalate or diallyl isophthalate employed for producing the toner are in the uncured or uncrosslinked state (often referred to in the art as a prepolymer), with the preferred polymers being the solid free flowing uncrosslinked homopolymers of diallyl phthalate and diallyl isophthalate. A particularly preferred uncrosslinked homopolymer of diallyl phthalate is a dry free flowing powder characterized by a softening range of 80 -105 C., and in addition has the following properties: Iodine No. of 55 and a specific gravity of 1.259, such a polymer being commercially available under the trademark Dapon 35. A particularly preferred uncrosslinked homopolymer of diallyl isophthalate is a dry free flowing powder characterized by a softening range of 55-95 C., and in addition has the following properties: Iodine No. 64 and a specific gravity of 1.256, such a polymer being commercially available under the trademark Dapon M.

The thermosetting resin comprises a substantial portion of the resin composition, generally from about 80% to about 100% of the resin composition, preferably from about 90 to about 95%, all by weight, with the remaining portion of the resin composition, if any, generally being a resin conventionally employed to modify the physical properties of a toner material; e.g., a long chain thermoplastic which has little tendency toward agglomeration or cold flow such as, polyvinyl butyral, polyethylene, shellac, waxes, polyesters, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate and the like. The resin modifier generally comprises from about 1% to about 20% of the resin composition preferably from about 5% to all by weight, with the remaining portion of the resin composition being the thermosetting resin.

The toner also includes a pigment or dye in a quantity suflicient to impart color to the resin composition, generally in a quantity from about 1% to about 20%, by weight, of the resin, whereby the resulting toner will form a clear visible image on a transfer member. Any one of a wide variety of pigments or dyes which do not adversely affect the properties of the toner may be employed to impart color to the resin; e.g., carbon black, a commercial red, blue or yellow dye, and since such dyes and/or pigments are well-known in the art, no detailed enumeration thereof is deemed necessary for a full understanding of the invention.

The toner may also include a suitable crosslinking catalyst for the thermosetting resin, generally one of the peroxide catalysts conventionally employed for crosslinking polymers of diallyl phthalate or isophthalate, preferable a solid catalyst, such catalysts being employed in an amount from 1-5%, by weight, of the thermosetting resin. The particular crosslinking catalyst employed must be a catalyst which does not effect premature crosslinking of the polymer, i.e., the catalyst does not initiate crosslinking of the polymer at temperatures employed in formulating the toner or during the development process prior to the fusing and crosslinking step to provide the permanent image. It is to be understood, however, that the polymers of diallyl phthalate and diallyl isophthalate may be crosslinked by the application of heat in the absence of a catalyst, although for some applications the use of a catalyst is preferred.

The colored toner may be prepared by any one of a wide variety of procedures for forming a uniform dispersion of the dye or pigment in the resinous material. Thus,

for example, the resinous material, the catalyst, if any, and a suitable pigment may be thoroughly mixed, for example, in a ball mill, and the resulting mixture heated to a temperature at which the resinous material flows without crosslinking. The molten resinous material is thoroughly mixed, and allowed to cool and harden to encase the pig ment within the resinous material. The pigmented or dyed resinous material is then micronized to particles having a particle size generally employed for a toner; generally a particle size of less than about 30 microns, preferably an average particle size from about 10 to about 20 microns.

Another procedure for producing the toner involves forming a solution or dispersion of the resinous portion of the toner, catalyst, if any, and the pigment or dye which is then micronized into fine droplets, for example, with a spinning disc atomizer, and spray dried to produce micronized solid particles of the pigmented or dyed resinous material.

The above procedures and other procedures for producing colored toner of the desired particle size are generally known in the art and may be employed for producing the toner of the present invention, provided such production is effected under conditions which do not cure or crosslink the thermosetting resin.

The hereinabove described toner of the invention may also include other materials generally employed for modifying the characteristics of a toner, such as, conductive materials to modify the triboelectric properties thereof, magnetic materials or the like, and the use of such materials is deemed to be within the scope of those skilled in the art from the teachings herein.

The toner hereinabove described, is employed in a developer composition by loosely coating the toner on a suitable electrostatographic developer carrier surface to which the toner is affixed by electrostatic attraction. Thus, for example, the toner composition may be employed in the cascade development technique, as more fully described in: US. Pat. No. 2,618,551 to Walkup, US. Pat. No. 3,618,552 to Wise; and US. Pat. No. 2,638,416 to Walkup et al. In the cascade development technique, the developer composition is produced by mixing the toner composition with a carrier, either electrically conducting or insulating, magnetic or non-magnetic, provided that the carrier material when brought in close contact with the toner composition acquires a charge having an opposite polarity to that of the toner whereby the toner adheres to and surrounds the carrier. Thus, the carrier material is selected in accordance with the triboelectric properties so that the toner is either above or below the carrier material in the triboelectric series, to provide a positively or negatively charged toner.

The carrier particles are larger than the toner particles by at least one order of magnitude of size and are shaped to roll across the latent image-bearing surface. In general, the carrier particles should be of sufficient size so that their gravitational or momentum force is greater than the force of attraction of the toner particles in the area of the image-bearing surface where the toner particles are retained, whereby the carrier will not be retained by the toner particles which are attracted to the image-bearing surface. The carrier particles generally have a particle size from about 30 to about 1000 microns, but it is to be understood, that the carrier particles may be of a size other than as particularly described, provided that the carrier flows easily over the image bearing surface, without requiring special means for effecting removal of the carrier particles from the image bearing surface.

The degree of contrast or other photographic qualities in the finished image may be varied by changing the relative proportions of toner and carrier material and the choice of optimum proportions is deemed to be within the scope of those skilled in the art. In general, however, the toner of the invention is employed in amounts to provide weight ratios of carrier to toner of from about 25:1 to

about 250:1, preferably from about 75:1 to about 100:1, to produce a dense readily transferable image.

In addition to the use of particles to provide the carrier surface, the bristles of a fur brush may also be used- Here also, the toner particles acquire an electrostatic charge of polarity determined by the relative position of the toner particles and the fur fibers in the triboelectric series. The toner particles form a coating on the bristles of the fur clinging thereto by reaason of the electrostatic attraction between the toner and the fur just as the toner clings to the surface of the carrier particles. The general process of fur brush development is described in greater detail in US. Pat. No. 3,251,706 to L. E. Walkup.

Even more closely related to the cascade carrier development is magnetic brush development. In this process a carrier is selected having ferromagnetic properties and selected relative to the toner in a triboelectric series so as to impart the desired electrostatic polarity to the toner and carrier as in cascade carrier development. On inserting a magnet into such a mixture of toner and magnetic material the carrier particles align themselves along the lines of force of the magnet to assume a brush-like array. The toner particles are electrostatically coated on the surface of the powder carrier particles. Development proceeds as in regular cascade carrier development on moving the magnet over the surface bearing the electrostatic image so that the bristles of the magnetic brush contact the electrostatic image-bearing surface.

Still another method of carrier development is known as sheet carrier development in which the toner particles are placed on a sheet as of paper, plastic, or metal. This process is described in U.'S. Pat. No. 2,895,847 to C. R. Mayo. As described therein the electrostatic attraction between the sheet surface and toner particles necessary to assure electrostatic attraction therebetween may be obtained by leading the sheet through a mass of electroscopic toner particles whereby there is obtained a rubbing or sliding contact between the sheet and the toner. In general it is desirable to spray the surface of the sheet bearing the electroscopic toner particles with ions of the desired polarity as by the use of a corona charging device as described in the patent of Mayo.

The resulting image of toner particles on the imagebearing surface may then be transferred to a suitable transfer member to form the final copy. The transfer of the toner particles may be effected adhesively or electrostatically and the resulting image on the transfer member is made permanent, by heating the toner particles to a temperature at which the resinous composition of the toner is crosslinked, generally a temperature from about 200 F. to about 700 F. It is to be understood that the amount of cross-linking effected in a function of both time and temperature and therefore it is to be understood that the final image may be formed without effecting complete crosslinking of the thermosetting resin. The selection of a particular crosslinking temperature and time to provide the final image having the desired storage properties at a desired production rate is deemed to be well within the scope of those skilled in the art from the teachings herein.

The toner as should be apparent from the hereinabove teachings, may be employed in a wide variety of developer compositions by electrostatically coating the toner composition to a suitable carrier surface, which is subsequently passed over a latent image bearing surface. The toner of the invention may also be employed for developing a latent-electrostatic image formed by other than electrophotographic means; for example, the development of latent electrostatic images formed by pulsing electrodes as employed in electrostatic printing processes. In addition, the toner of the invention may be employed for developing a latent electrostatic image on a surface other than a photoconductive insulating surface. Therefore, the overall invention is not limited to a specific technique for 6 forming or developing a latent-electrostatic image or to a specific carrier for the toner.

The invention is further described with reference to the following examples which are illustrative of preferred embodiments of the invention but it is to be understood that the scope of the invention is not to be limited thereby. It is to be understood that all reference to parts and percentages in such examples are by weight.

Example I A resin composition comprised of parts of an uncrosslinked homopolymer of diallyl phthalate having a softening range of 80-l05 C. (Dapon 35, sold by Food Machinery & Chemical Corp.) and 10 parts of polyvinyl chloride are dispersed in methyl ethyl ketone with 1 part, based on the resin composition, of blue redox dye, the solid concentration being 15%.

The dispersion is micronized into fine droplets by a spinning disc atomizer and contacted with hot air in a conical type spray drier to produce dry toner particles, which are partially classified in a cyclone collecting chamber, to particles having a size ranging from 620 microns.

The toner is then combined with an electrostatographic developer carrier, comprised of 250 micron steel beads coated with styrene-methyl methacrylate vinyl triethoxysilane polymer, to provide a developer composition comprised of 1 part toner and parts carrier.

The developer composition is cascaded (3 cycles) over a fiat selenium plate, bearing a latent electrostatic image, and the deposited toner electrostatically transferred to paper whereon the powder is fused and crosslinked to produce a print of good density and low background. In addition, the toner is easily transferred from the plate to the paper and any residual toner remaining on the selenium plate is easily removed.

Example II A resin composition comprised of 90 parts of an uncrosslinked homopolymer of diallyl isophthalate having a softening range of 55 -9S C. (Dapon M sold by Food Machinery and Chemical Corp.) and 10 parts of polyvinyl chloride are dispersed in methyl ethyl ketone with 10 parts, based on the resin composition, of carbon black, the solid concentration being 20%.

The dispersion is micronized into fine droplets by a spinning disc atomizer and contacted with hot air in a conical type spray drier to produce dry toner particles, which are partially classified in a cyclone collecting chamber, to particles having a size ranging from 620 microns.

The toner is then combined with an electrostatographic developer carrier comprised of 250 micron steel beads coated with styrene-methyl methacrylate-vinyl triethoxysilane polymer, to provide a developer composition comprised of 1 part toner and 100 parts carrier.

The developer composition is cascaded (3 cycles) over a fiat selenium plate, bearing a latent electrostatic image, and the deposited toner electrostatically transferred to paper whereon the powder is fused and crosslinked to produce a print of good density and low background. In addition, the toner is easily transferred from the plate to the paper and any residual toner remaining on the selenium plate is easily removed.

Example III A prepolymer of diallyl phthalate (Dapon 35) is dispersed in methyl ethyl ketone with 1 part, based on the resin composition, of blue redox dye, the said concentration being 20%.

The dispersion is micronized into fine droplets by a spinning disc atomizer and contacted with hot air in a conical type spray drier to produce dry toner particles, which are partially classified in a cyclone collecting chamber to particles having a size ranging from 6-20 microns.

The toner is then combined with an electrostatographic developer carrier comprised of 250* micron steel beads coated with styrene-methyl methacrylate-vinyl triethoxysilane polymer, to provide a developer composition comprised of 1 part toner and 100 parts carrier.

The developer composition is cascaded (3 cycles) over a fiat selenium plate, bearing a latent electrostatic image and the deposited toner electrostatically transferred to paper whereon the powder is fused and crosslinked to produce a print of good density and low background. In addition, the toner is easily transferred from the plate to the paper and any residual toner remaining on the selenium plate is easily removed.

Example IV A resin composition comprised of parts of a prepolymer of diallyl isophthalate (Dapon M) and 10 parts of polyvinyl chloride are dispersed in methyl ethyl ketone with 1 part, based on the resin composition, of blue redox dye, the solid concentration being 10%.

The dispersion is micronized into fine droplets by a spinning disc atomizer and contacted with hot air in a conical type drier to produce dry toner particles, which are partially classified in a cyclone collecting chamber to particles having a size ranging from 6-20 microns.

The toner is then combined with an electrostatographic developer carrier comprised of sand coated with ethyl cellulose to provide a developer composition comprised of 1 part toner and 100 parts carrier.

The developer composition is cascaded (3 cycles) over a fiat selenium plate, bearing a latent electrostatic image, and the deposited toner electrostatically transferred to paper whereon the powder is fused and crosslinked to produce a print of good density and low background. In addition, the toner is easily transferred from the plate to the paper and any residual toner remaining on the selenium plate is easily removed.

Example V A resin composition comprised of 80 parts of a prepolymer of diallyl phthalate (Dapon 35) and 20 parts of polyvinyl butyral are dispersed in methyl ethyl ketone with 10 parts, based on the resin composition, of carbon black, the solid concentration being 20%.

The dispersion is micronized into fine droplets by a spinning disc atomizer and contacted with hot air in a conical type spray drier to produce dry toner particles, which are partially classified in a cyclone collecting chamber to particles having a size ranging from 6-20 microns.

The toner is then combined with an electrostatographic developer carrier which is prepared in accordance with Example I of U.S. Pat. No. 2,618,551 to Walkup, to provide a developer composition comprised of 1 part toner and 100 parts carrier.

The developer composition is cascaded (3 cycles) over a flat selenium plate, bearing a latent electrostatic image, and the deposited toner electrostatically transferred to paper whereon the powder is fused and crosslinked to produce a print of good density and low background. In addition, the toner is easily transferred from the plate to the paper and any residual toner remaining on the selenium plate is easily removed.

Example VI A resin composition comprised of 95 parts of a prepolymer diallyl phthalate (Dapon 35 and 5 parts of polyethylene are dispersed in methyl ethyl ketone with 1 part, based on the resin composition of blue redox dye, the solid concentration being 20%.

The dispersion is micronized into fine droplets by a spinning disc atomizer and contacted with hot air in a conical type spray drier to produce dry toner particles, which are partially classified in a cyclone collecting chamber to particles having a size ranging from 6-20 microns.

The toner is then combined with an electrostatographic developer carrier comprised of 250 micron steel beads coated with styrene-methyl methacrylate-vinyl triethoxysilane polymer, to provide a developer composition comprised of 1 part toner and 100 parts carrier.

The developer composition is cascaded (3 cycles) over a fiat selenium plate, bearing a latent electrostatic image, and the deposited toner electrostatically transferred to paper whereon the powder is fused and crosslinked to produce a print of good density and low background. In addition, the toner is easily transferred from the plate to the paper and any residual toner remaining on the selenium plate is easily removed.

Example VII The procedure of Example I is repeated using a 1:1 mixture of diallyl phthalate prepolymer (Dapon 35 and diallyl isophthalate prepolymer (Dapon M) as the thermosetting resin with equally good results.

The toner of the present invention is particularly advantageous in that the permanent toner images produced therewith are thermoset and therefore, unlike final toner images produced with the thermoplastic toners, the toner images produced in accordance with the present invention do not become tacky when stored in a warm place or placed in contact with plasticized plastic surfaces. In addition, the toner of the present invention is chemically inert and compatible with a wide range of resins, thereby permitting facile modification of the physical properties thereof. Furthermore, the toner is very friable which facilitates the production of small particles thereof.

Numerous modifications and variations of the invention are possible in light of the above teaching and therefore the invention may be practised in a manner other than as particularly described.

What is claimed is:

1. An electrostatographic developer comprising: a finely divided colored resin on a carrier, a substantial portion of the resin being a solid free-flowing uncrosslinked thermosetting resin selected from the group consisting of polymers of diallyl phthalate, polymers of diallyl isophthalate and mixtures thereof.

2. The electrostatographic developer as defined in claim 1 wherein the resin comprises at least about by weight, of an uncrosslinked homopolymer of diallyl phthalate.

3. The electrostatographic developed as defined in claim 1 wherein the resin comprises at least about 80%, by weight, of a uncrosslinked homopolymer of diallyl isophthalate.

4. An electrostatographic developer comprising toner on a carrier, said toner comprising a resin and a pigment or dye, said pigment or dye being present in an amount from about 1 part to about 20 parts, per parts of the resin, all by weight, said resin containing at least about 80%, by weight, of a solid free-flowing uncrosslinked thermosetting resin selected from the group consisting of polymers of diallyl phthalate, polymers of diallyl isophthalate and mixtures thereof.

5. The developer as defined in claim 4 wherein the thermosetting resin is an uncrosslinked homopolymer of diallyl phthalate.

6. The developer as defined in claim 4 wherein the thermosetting resin is an uncrosslinked homopolymer of diallyl isophthalate.

7. An electrostatographic developer composition comprising: finely divided toner on a carrier, said toner comprising a resin and a pigment or dye, said resin containing at least about 80%, by weight, of a solid free-flowing uncrosslinked homopolymer of diallyl phthalate having a softening point range of 80l05 C.

8. An electrostatographic developer as defined in claim 7 wherein the resin further includes from about 1% to about 20%, by weight, of a long chain thermoplastic resin modifier with the remaining portion of the resin being the uncrosslinked homopolymer of diallyl phthalate and said pigment or dye is present in amount from about 9 1 part to about parts per 100 parts of the resin, all by weight.

9. The developer as defined in claim 8 wherein the toner has a particle size of less than about 30 microns.

10. The developer as defined in claim 9 wherein said carrier is a carrier shaped to roll across an image-bearing surface.

11. The developer as defined in claim 9 wherein the modifier is polyvinyl chloride.

12. The developer as defined in claim 9 wherein the toner further includes a crosslinking catalyst for the uncrosslinked homopolymer of diallyl phthalate.

13. An electrostatographic developer composition comprising: finely divided toner on a carrier, said toner comprising a resin and a pigment or dye, said resin containing at least about 80%, by weight, of a solid free-flowing uncrosslinked homopolymer of diallyl isophthalate having a softening point range of 55-95 C.

14. An electrostatographic developer as defined in claim 13 wherein the resin further includes from about 1% to about 20%, by weight, of a long chain thermoplastic resin modifier with the remaining portion of the resin being the uncrosslinked homopolymer of diallyl isophthalate and said pigment or dye is present in an amount from about 1 part to about 20 parts per 100 parts of the resin, all by weight.

15. The developer as defined in claim 14 wherein the toner has a particle size of less than about 30 microns.

16. The developer as defined in claim 15 wherein said carrier is a carrier shaped to roll across an image-bearing surface.

17. The developer as defined in claim 15 wherein the modifier is polyvinyl chloride.

18. The developer as defined in claim 15 wherein the toner further includes a crosslinking catalyst for the uncrosslinked homopolymer of diallyl isophthalate.

19. A process for providing a visible image from an electrostatic latent image, comprising:

developing the electrostatic latent image with a toner 10 comprising a finely divided colored resin, a substantial portion of the resin being a solid free-flowing uncrosslinked thermosetting resin selected from the group consisting of polymers of diallyl phthalate, polymers of diallyl isophthalate and mixtures thereof.

20. The process as defined in claim 19 wherein the resin comprises at least about percent, by weight, of an uncrosslinked homopolymer of diallyl isophthalate having a softening range of 55 C. to C.

21. The process as defined in claim 19 wherein the resin comprises at least about 80 percent, by weight, of an uncrosslinked homopolymer of diallyl phthalate having a softening range of 80 C. to 105 C.

22. The process as defined in claim 19 wherein the electrostatic latent image is on a photoconductive insulating surface and said electrostatic latent image is formed by exposing the surface with an electrostatic charge thereon to a light and shadow image to dissipate the charge on the areas exposed to light and thereby form said electrostatic latent image.

23. The process as defined in claim 22 and further comprising: transferring said toner particles in image configuration on said transfer member; and heating the resulting image on the transfer member to crosslink the thermosetting resin and thereby provide a final copy.

References Cited UNITED STATES PATENTS 3,502,582 3/1970 Clemens et al. 252-62.1 3,093,039 6/1963 Rheinfrank 25262.1 3,376,139 4/1968 Gialgualane et al. 96-115 RX ROLAND E. MARTIN, JR., Primary Examiner U.S. Cl. X.R.

252-62.1', l17-l00A, 100M, 100 C, 17.5 

